This patch provides the possibility to adjust the default value for
"maximum expected number of bad blocks per 1024 blocks" from kernel
configuration.
sam9_l9260_defconfig has been adjusted as well. The nand device used by
this card has a NVB of 3996/4096 ie a MAX_BEB_LIMIT of 25/1024
Signed-off-by: Richard Genoud <richard.gen...@gmail.com>
---
arch/arm/configs/sam9_l9260_defconfig | 1 +
drivers/mtd/ubi/Kconfig | 29 +++++++++++++++++++++++++++++
drivers/mtd/ubi/ubi.h | 2 +-
3 files changed, 31 insertions(+), 1 deletions(-)
diff --git a/arch/arm/configs/sam9_l9260_defconfig
b/arch/arm/configs/sam9_l9260_defconfig
index 47dd71a..2c20c9e 100644
--- a/arch/arm/configs/sam9_l9260_defconfig
+++ b/arch/arm/configs/sam9_l9260_defconfig
@@ -39,6 +39,7 @@ CONFIG_MTD_NAND=y
CONFIG_MTD_NAND_ATMEL=y
CONFIG_MTD_NAND_PLATFORM=y
CONFIG_MTD_UBI=y
+CONFIG_MTD_UBI_DEFAULT_BEB_LIMIT=25
CONFIG_MTD_UBI_GLUEBI=y
CONFIG_BLK_DEV_LOOP=y
CONFIG_BLK_DEV_RAM=y
diff --git a/drivers/mtd/ubi/Kconfig b/drivers/mtd/ubi/Kconfig
index 7a57cc0..30e8370 100644
--- a/drivers/mtd/ubi/Kconfig
+++ b/drivers/mtd/ubi/Kconfig
@@ -27,6 +27,35 @@ config MTD_UBI_WL_THRESHOLD
life-cycle less than 10000, the threshold should be lessened (e.g.,
to 128 or 256, although it does not have to be power of 2).
+config MTD_UBI_DEFAULT_BEB_LIMIT
+ int "Maximum expected bad eraseblock count per 1024 eraseblocks"
+ default 20
+ range 0 256
+ help
+ This option specifies the default value for maximum bad physical
+ eraseblocks UBI expects on the MTD device (per 1024 eraseblocks).
+ It will be used when the maximum bad PEB value is null in the
+ UBI_IOCATT ioctl (e.g. when calling ubiattach) or in the kernel
+ parameter ubi.mtd.
+ If the underlying flash does not admit of bad eraseblocks
+ (e.g. NOR flash), this value is ignored.
+
+ NAND datasheets often specify the minimum and maximum NVM (Number of
+ Valid Blocks) for the flashes' endurance lifetime. The maximum
+ expected bad eraseblocks per 1024 eraseblocks then can be calculated
+ as "1024 * (1 - MinNVB / MaxNVB)", which gives 20 for most NANDs
+ (MaxNVB is basically the total count of eraseblocks on the chip).
+
+ To put it differently, if this value is 20, UBI will try to reserve
+ about 1.9% of physical eraseblocks for bad blocks handling. And that
+ will be 1.9% of eraseblocks on the entire NAND chip, not just the MTD
+ partition UBI attaches. This means that if you have, say, a NAND
+ flash chip that admits a maximum 40 bad eraseblocks, and it is split
+ on two MTD partitions of the same size, UBI will reserve 40
+ eraseblocks when attaching a partition.
+
+ Leave the default value if unsure.
+
config MTD_UBI_GLUEBI
tristate "MTD devices emulation driver (gluebi)"
help
diff --git a/drivers/mtd/ubi/ubi.h b/drivers/mtd/ubi/ubi.h
index f926343..39a1e7e 100644
--- a/drivers/mtd/ubi/ubi.h
+++ b/drivers/mtd/ubi/ubi.h
@@ -51,7 +51,7 @@
#define UBI_NAME_STR "ubi"
/* Default number of maximum expected bad blocks per 1024 eraseblocks */
-#define MTD_UBI_DEFAULT_BEB_LIMIT 20
+#define MTD_UBI_DEFAULT_BEB_LIMIT CONFIG_MTD_UBI_DEFAULT_BEB_LIMIT
/* Normal UBI messages */
#define ubi_msg(fmt, ...) printk(KERN_NOTICE "UBI: " fmt "\n", ##__VA_ARGS__)
--
1.7.2.5
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